Simple texture blending shader that blends 3 textures of varying tiling and offsets.

TextureBlendShader.shader

Shader "Custom/TextureBlendShader"
{
    Properties
    {
        _MainTex01 ("Texture01", 2D) = "white" {}
        _MainTex02 ("Texture02", 2D) = "white" {}
        _MainTex03 ("Texture03", 2D) = "white" {}
        [Header(Fragment RGBA Multipliers)]
        _FragR ("FragR", Range(0,5)) = 1
        _FragG ("FragG", Range(0,5)) = 1
        _FragB ("FragB", Range(0,5)) = 1
        _FragA ("FragA", Range(0,5)) = 1
    }
    SubShader
    {
        Tags { "RenderQueue"="Geometry" }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            sampler2D _MainTex01; float4 _MainTex01_ST;
            sampler2D _MainTex02; float4 _MainTex02_ST;
            sampler2D _MainTex03; float4 _MainTex03_ST;
            float _FragR; float _FragG; float _FragB; float _FragA;

            float Remap(float value, float low1, float high1, float low2, float high2)
            {
                return low2 + (value - low1) * (high2 - low2) / (high1 - low1);
            }

            void vert (
                float4 pos : POSITION,
                out float4 opos : SV_POSITION,
                float2 texCoord0 : TEXCOORD0,
                out float4 otexCoord0 : TEXCOORD0,
                out float4 otexCoord1 : TEXCOORD1
            )
            {
                opos = UnityObjectToClipPos(pos);
                _MainTex01_ST.z = sin(radians(_Time.x));
                _MainTex01_ST.w = sin(radians(_Time.x/10));
                _MainTex02_ST.z = _Time.x/5;
                _MainTex02_ST.w = -(_Time.x/10);
                _MainTex03_ST.z = -(_Time.x/9);
                _MainTex03_ST.w = sin(radians(_Time.x/5))*2;
                _MainTex01_ST.x = Remap(sin(radians(_Time.y)),-1,1,1,1.5);
                _MainTex01_ST.y = Remap(sin(radians(_Time.z/2)),-1,1,0.6,1.2);
                _MainTex02_ST.x = Remap(sin(radians(_Time.x/5)),-1,1,0.5,1);
                _MainTex02_ST.y = Remap(sin(radians(_Time.x/7)),-1,1,1,2);
                _MainTex03_ST.x = Remap(sin(radians(_Time.x/15)),-1,1,1,1.5);
                _MainTex03_ST.y = Remap(cos(radians(_Time.x/15)),-1,1,0.6,1.5);
                
                otexCoord0.xy = texCoord0.xy * _MainTex01_ST.xy + _MainTex01_ST.zw;
                otexCoord0.zw = texCoord0.xy * _MainTex02_ST.xy + _MainTex02_ST.zw;
                otexCoord1.xy = texCoord0.xy * _MainTex03_ST.xy + _MainTex03_ST.zw;
                otexCoord1.zw = 0;
            }

            float4 frag (
                float4 pos : SV_POSITION,
                float4 texCoord0 : TEXCOORD0,
                float4 texCoord1 : TEXCOORD1
            ) : SV_TARGET
            {
                float4 col1 = tex2D(_MainTex01, texCoord0.xy);
                float4 col2 = tex2D(_MainTex01, texCoord0.zw);
                float4 col3 = tex2D(_MainTex01, texCoord1.xy);
                float4 fcol = float4(lerp(col1.rgb, col2.rgb, min(col1.r, col2.r)),1);
                fcol.rgb = lerp(fcol.rgb, col3.rgb, min(col2.r, col3.r));
                fcol.r *= _FragR;
                fcol.g *= _FragG;
                fcol.b *= _FragB;
                fcol.a *= _FragA;
                
                return fcol;
            }

            ENDCG
        }
    }
}